If thats what type of rack you are planning on building, why not use back heat?
If you look a couple posts down you can see the rack I just built, it uses sliders, therefore belly heat would be a lot easier to use.
WIth your rack, you can get 11" Flexwatt and run it down the bottom of each row, maybe even 4". Get a couple helix's and you'd be set. 
>>im sorry, that was very unclear.
>>
>>im building a rack system with rubbermaid tubs. the tubs do not have a lid, you just slide them out from under the next shelf.
>>
>>kind of like this:
>>http://www.boaphileplastics.com/blanketrack.html
>>
>>but 3 or 4 tubs wide instead of 1.
>>
>>thanks
>>
>>-z
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- Joel Smith
"If you're not part of the solution, you're still part of the problem"